This application is to renew the T32 ES09250-25 training grant entitled, Environmental Carcinogenesis and Mutagenesis (ECM) which has been under the direction of Dr. Stambrook since its inception in 1986. Dr. Alvaro Puga has been a mentor in the Program since early in its history and has served as Associate Director for the past five-year budget period, a role in which he will continue. The focus of the ECM training program initially was exclusively on environmental carcinogenesis and mutagenesis as its title implied. Since that time, the Program has evolved scientifically and conceptually. It also grew from its modest beginnings to its current optimal size when the NIEHS directed that it be merged with a smaller training program in toxicology. By this merger, the Program became more diverse which has proven to be extremely valuable to the trainees. The investigators have, therefore, made every effort to retain this diversity of disciplines to enhance cross-fertilization of ideas and techniques between the trainees. Thus, the trainees are able to cogently discuss the impact of environmental exposures in terms of genetics and toxicology and ultimately in the context of human disease, including cancer. One of the emphases of the ECM Training Program is to train the fellows to appreciate the mechanistic relationships between environmental challenges and their toxicological and carcinogenic outcomes. The consequence of this strategy has been a robust cross-fertilization of ideas and approaches. To preserve this wide range of disciplines, the Program maintains a participating faculty who derive from seven different departments. Thus, the ECM continues to build on its past successes, with graduates in academic, regulatory and industry leadership positions and it continues to fulfill a national need to train individuals in the impact of environmental exposure relating to biological, oncological and toxicological endpoints and human disease. Since its inception, the Program has emphasized recruitment of under-represented minorities, and has been successful in this endeavor. Institutionally, the Program brings together the research efforts of several laboratories to provide a common focus on exposure and environmental health, and facilitates collaborations between these laboratories. The ECM encourages trainees to engage in research that combines the expertise of several laboratories. These interactions are facilitated by biweekly journal club meetings where trainees alternatively present a topical paper or present their data. Pre-doctoral trainees all have the equivalent of an undergraduate major in a chemical, biological or physical science with superior academic achievements. Many have won awards and recognition while in the Program. Postdoctoral candidates are selected based on proven academic accomplishments and hold the degrees of Ph.D., D.V.M. or M.D., and like pre-doctoral trainees are selected from a national pool of applicants. This renewal application requests pre-doctoral (8) and postdoctoral (4) positions, a size that the investigators find optimal for the mission and goals of this Program.